This invention relates to valves used with diving suits, and more particularly to an improved valve for controlling the release of excess quantities of gas from within a diving suit.
Some diving suits, of the type known as dry suits because they are intended to keep the diver dry, are designed to utilize a portion of the diver's pressurized breathing gas supply to provide a thermally insulating layer of gas between the diver's body and the inner surface of the suit, or between inner and outer walls of a suit having a double wall construction. This is accomplished by diverting some of the breathing gas into the body portion of the suit until the layer of gas therein is at a pressure substantially at or slightly above the ambient water pressure. The gas is usually air but may comprise other breathable gas mixtures. For convenience, the term air as used hereinafter will be understood to include any such mixtures.
While the layer of entrapped air provides a significant degree of useful thermal insulation to the diver, it expands in volume as the diver moves from deeper depths to shallower depths, due to the attendant decreases in ambient pressure. This expansion increases the total buoyancy of the diver's suit, thereby tending to cause the diver to rise further to a still shallower depth, and in turn causing further expansion of the air and increase in suit buoyancy. With no provision for venting excess air as a diver moves to shallower depths, the diver would tend to rise at an unsafe ascent rate. Too rapid ascent of the diver can result in serious physiological problems.
A variety of early diving suits have incorporated simple rubber check valves of disc or flapper type for venting of excess suit gas during ascent or change in attitude. Examples of these are found in U.S. Pat. No. 2,593,988 of J. Y. Cousteau and U.S. Pat. No. 3,024,465 of G. Bould. Those valves, however, are subject to being forced inwardly of their seats in the event increases in suit pressure do not adequately follow increases in ambient pressures, such as during a rapid, even momentary descent.
Presently, suit exhaust valves having the primary purpose of controlling the release of excess air during ascent as opposed to exhaust valves for discharging expired air, are designed for either of two different operational modes. The most common mode is for the diver to vent the excess air by depressing an exhaust valve actuator by hand so as to relieve the force of an internal spring sufficiently to permit the valve to be opened by the excess pressure of the internally trapped air. As long as the diver holds the actuator depressed the excess air escapes, until the internal air pressure is substantially reduced to the ambient water pressure at which time a safety one-way valve feature prevents water from entering the suit. A second type of valve in current use differs in operation in that the diver pulls a tether to hold a valve open against the pressure of an internal spring to allow the excess air to escape. This type of valve does not have the one-way safety valve feature and, if the diver fails to release the tether soon enough, water will enter the suit when excess air has been released and the suit will not remain dry.
One of the major disadvantages of either of the above operational modes is the requirement of the diver to manually operate the valve throughout his ascent, thereby precluding use of one hand for other important purposes. Another shortcoming of the known valves for the purpose is the use of springs to hold the valve closed when released. Spring actuated devices are notoriously unreliable in the environments of mud, sand and silt common to diving work. Additionally, manually depressible buttons and pull tethers are often difficult to manage with a heavily gloved or mittened diver's hand.